A prior operating cylinder of the aforementioned type is described in German OS No. 27 18 639. However, its piston does not have any exactly presettable operating positions.
An object of the present invention is to provide an improved operating cylinder of the aforementioned type, improved so that the piston is moved, through pressure admission or under the spring force, into exactly preselectable operating end positions, and wherein the inventive operating cylinder is compact, as needed for a plurality of uses, for example as a servomotor in industrial sewing machines.
In the inventive operating cylinder, a spring arrangement and a stop mechanism which control the end positions of the piston are stored within the volume of the piston, and thus do not need any additional space. A further advantage of the inventive operating cylinder is that one can build the spring arrangement of commercial helical coil compression springs, while the above-mentioned known operating cylinder has a special spring with a rectangular coil cross section.